A009647 Expansion of tan(log(1+x))/cosh(x).

0, 1, -1, 1, -12, 95, -615, 5003, -52192, 600029, -7464645, 102853749, -1558643724, 25565811531, -450966117147, 8528942156655, -172180452813600, 3693485934629625, -83891436038405865, 2011562464233339561

Offset

0,5

Links

Table of n, a(n) for n=0..19.

Formula

a(n) ~ n! * (-1)^(n+1) / ((exp(Pi/2)-1) * cosh(1-exp(-Pi/2)) * (1-exp(-Pi/2))^n). - Vaclav Kotesovec, Jan 23 2015

Mathematica

Tan[ Log[ 1+x ] ]/Cosh[ x ]
CoefficientList[Series[Sech[x]*Tan[Log[1 + x]], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 23 2015 *)

Crossrefs

Sequence in context: A045894 A045829 A220683 * A038836 A026860 A021074

Adjacent sequences: A009644 A009645 A009646 * A009648 A009649 A009650

Keyword

sign,easy

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Status

approved